Somchaya:
So.. I'm wondering whether I should use a single omnidirectional wheel or a usual swivel castor for my differential drive robot.

I like the idea of using the omni wheel, but I'm not very sure on how to mount it properly as a castor. Using a normal swivel castor helps in that aspect, since it's easier to mount, but I'm wondering if it'll affect the robot's performance in general.

Any suggestions?

annoyin_kid:
i dont think it will make much difference which wheel you use. the advantage with castor is that it is less $$$ to fork out (and you could always pull it off some furniture and try to see if it works) and if it screws up you can upgrade to the onmi wheel knowing that the castor wont do any good.

JesseWelling:
well mechanically speaking the omni has less adverse effects on the drive motors than a castor wheel.Because the axel of the castor wheel is offset from the vertical axis of rotation there is often a some weird issues when first moving in a different direction. You will notice this effect in office chairs when you rollforward and back as the castors swap directions. I would go with an omni wheel for this reason, especially if youare going to operate the robot on carpet or any thing that will significantly grip the castor wheel.

Steve Joblin:
You may also want to consider a "ball caster"... McMaster-Carr has a very nice selection... goto http://www.mcmaster.com/ , then type in "ball transfers"

Admin:
i have a ball caster that i used to use . . . but i dont like them because they are heavy and cant handle rough terrain

for non-rough terrain, they are probably the lowest friction in the bunch

i own and have used all three caster types for robots, but i prefer omni-wheels the most ;D